Re: [patch] PR66714 -- Re: Re: [RFC] two-phase marking in gt_cleare_cache

[Cesar Philippidis <cesar_philippidis at mentor dot com>]

On 07/23/2015 03:11 PM, Jakub Jelinek wrote:
> On Thu, Jul 23, 2015 at 03:01:25PM -0700, Cesar Philippidis wrote:
>> On 07/23/2015 08:32 AM, Jakub Jelinek wrote:
>>> On Thu, Jul 23, 2015 at 08:20:50AM -0700, Cesar Philippidis wrote:
>>>> The attached patch does just that; it teaches
>>>> replace_block_vars_by_duplicates to replace the decls inside the
>>>> value-exprs with a duplicate too. It's kind of messy though. At the
>>>> moment I'm only considering VAR_DECL, PARM_DECL, RESULT_DECL, ADDR_EXPR,
>>>> ARRAY_REF, COMPONENT_REF, CONVERT_EXPR, NOP_EXPR, INDIRECT_REF and
>>>> MEM_REFs. I suspect that I may be missing some, but these are the only
>>>> ones that were triggered gcc_unreachable during testing.
>>>
>>> Ugh, that looks ugly, why do we have all the tree walkers?
>>> I'd unshare_expr the value expr first, you really don't want to share
>>> it anyway, and then just walk_tree and find all the decls in there
>>> (with *walk_subtrees on types and perhaps something else too) and for them
>>> replace_by_duplicate_decl (tp, vars_map, to_context);
>>
>> Something like the attached patch? Why do TREE_TYPEs need special handling?
> 
> They can have decls in various places like TYPE_SIZE_UNIT, TYPE_SIZE, the
> bounds of TYPE_DOMAIN etc. and I believe you generally don't want to replace
> those.  Plus you risk infinite recursion then (unless walk_tree_without_duplicates).
> Most walk_tree callbacks just do something like
>   if (IS_TYPE_OR_DECL_P (*tp))
>     *walk_subtrees = 0;

This patch the check for IS_TYPE_OF_DECL_P in this patch. Is this ok for
trunk?

Cesar

2015-07-24  Cesar Philippidis  <cesar@codesourcery.com>

	gcc/
	* tree-cfg.c (struct replace_decls_d): New struct.
	(replace_block_vars_by_duplicates_1): New function.
	(replace_block_vars_by_duplicates): Use it to replace the decls
	in the value exprs by duplicates.

	libgomp/
	* testsuite/libgomp.c/pr66714.c: New test.
	

diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index fde7fbc..cb9fe6d 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -70,6 +70,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "omp-low.h"
 #include "tree-cfgcleanup.h"
 #include "wide-int-print.h"
+#include "gimplify.h"
 
 /* This file contains functions for building the Control Flow Graph (CFG)
    for a function tree.  */
@@ -108,6 +109,13 @@ struct cfg_stats_d
 
 static struct cfg_stats_d cfg_stats;
 
+/* Data to pass to replace_block_vars_by_duplicates_1.  */
+struct replace_decls_d
+{
+  hash_map<tree, tree> *vars_map;
+  tree to_context;
+};
+
 /* Hash table to store last discriminator assigned for each locus.  */
 struct locus_discrim_map
 {
@@ -6897,6 +6905,31 @@ new_label_mapper (tree decl, void *data)
   return m->to;
 }
 
+/* Tree walker to replace the decls used inside value expressions by
+   duplicates.  */
+
+static tree
+replace_block_vars_by_duplicates_1 (tree *tp, int *walk_subtrees, void *data)
+{
+  struct replace_decls_d *rd = (struct replace_decls_d *)data;
+
+  switch (TREE_CODE (*tp))
+    {
+    case VAR_DECL:
+    case PARM_DECL:
+    case RESULT_DECL:
+      replace_by_duplicate_decl (tp, rd->vars_map, rd->to_context);
+      break;
+    default:
+      break;
+    }
+
+  if (IS_TYPE_OR_DECL_P (*tp))
+    *walk_subtrees = false;
+
+  return NULL;
+}
+
 /* Change DECL_CONTEXT of all BLOCK_VARS in block, including
    subblocks.  */
 
@@ -6916,7 +6949,11 @@ replace_block_vars_by_duplicates (tree block, hash_map<tree, tree> *vars_map,
 	{
 	  if (TREE_CODE (*tp) == VAR_DECL && DECL_HAS_VALUE_EXPR_P (*tp))
 	    {
-	      SET_DECL_VALUE_EXPR (t, DECL_VALUE_EXPR (*tp));
+	      tree x = DECL_VALUE_EXPR (*tp);
+	      struct replace_decls_d rd = { vars_map, to_context };
+	      unshare_expr (x);
+	      walk_tree (&x, replace_block_vars_by_duplicates_1, &rd, NULL);
+	      SET_DECL_VALUE_EXPR (t, x);
 	      DECL_HAS_VALUE_EXPR_P (t) = 1;
 	    }
 	  DECL_CHAIN (t) = DECL_CHAIN (*tp);
diff --git a/libgomp/testsuite/libgomp.c/pr66714.c b/libgomp/testsuite/libgomp.c/pr66714.c
new file mode 100644
index 0000000..c9af4a9
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c/pr66714.c
@@ -0,0 +1,17 @@
+/* { dg-do "compile" } */
+/* { dg-additional-options "--param ggc-min-expand=0" } */
+/* { dg-additional-options "--param ggc-min-heapsize=0" } */
+/* { dg-additional-options "-g" } */
+
+/* Minimized from on target-2.c.  */
+
+void
+fn3 (int x)
+{
+  double b[3 * x];
+  int i;
+#pragma omp target
+#pragma omp parallel for
+  for (i = 0; i < x; i++)
+    b[i] += 1;
+}